Ever increasing requirements for information systems to be available on a nearly constant, non-stop basis have motivated the development of high availability systems. These systems include high availability storage systems. Unfortunately, storage media is a major point of failure in any information system. Traditionally, various methods are employed to reduce the probability of failure and to allow recovery after a storage failure has occurred.
A virtualized cluster is a cluster of different storage nodes that together expose a single storage device. Input/Output operations (“I/Os”) sent to the cluster are internally re-routed to read and write data to the appropriate locations. In this regard, a virtualized cluster of storage nodes can be considered analogous to collection of disks in a Redundant Array of Inexpensive Disks (“RAID”) configuration, since a virtualized cluster hides the internal details of the cluster's operation from initiators and presents a unified device instead.
In a virtualized cluster, data may also be mirrored between two, or more, storage nodes to provide a redundancy-protected, high availability system. Data can be protected by storing copies in two locations. When two storage nodes are involved, various failures can result in the two nodes losing synchronization with one another. This loss of synchronization can occur in such a way that the two nodes are not able to resolve which one of them has the latest (correct) data. In effect, each node is operating as if it is the other node that has failed. Thus, the two nodes cannot be properly resynchronized. This pathological state may be referred to as a split brain condition, or split brain syndrome. With only two storage nodes in play, there are no additional nodes that can be used to “break the tie” between the conflicting storage nodes. Thus a costly, time consuming, and error prone human intervention may be required to establish a reliable resynchronization between the two storage nodes.
It is with respect to these considerations and others that the disclosure made herein is presented.